Watersheds
A watershed is the land area within which rainwater, snowmelt, and other precipitation drains into a particular river or segment of a river. Another name for watershed is “basin”.
Much of the precipitation that falls on the land, becomes “run-off” that moves along the land surface until it drains into small creeks which in turn drain into larger creeks and then rivers. Some of the precipitation infiltrates the soil and moves downward where it becomes groundwater. Some of the groundwater flows beneath the land surface until it discharges back into the major streams and rivers. In the urban portions of the watershed, streets, sidewalks, driveways, parking lots, businesses, and homes cover the drainage area with impervious surfaces. In these areas storm sewers serve as man-made ‘tributaries’ that collect the run-off and direct it to a nearby stream.
The Great Miami watershed includes approximately 5,385 square miles of land that drains into the Great Miami River. The watershed includes all or portions of 15 Ohio Counties and 3 Indiana Counties. The Great Miami River flows from northeast to southwest through southwest Ohio and eventually drains into the Ohio River near Cincinnati.
The Little Miami watershed covers approximately 1,757 square miles and includes all or portions of 9 Ohio counties. The Little Miami River has state and national Scenic River status and contains the longest Exceptional Warmwater Habitat (EWH) segment of any stream or river in Ohio . It flows to the southwest and drains into the Ohio River east of Cinncinnati.